1. Field of the Invention
The present invention relates to a data storage system which is arranged to connect to a changeable optical disk drive having a capability of storing different kinds of optical disks with the same form but various kinds of data formats to a host computer through an interface so that the host computer may control the changeable optical disk drive.
2. Description of the Related Art
Storage of recording media such as an optical disk where data is recorded in a unique storage unit is effective in managing two or more recording media.
For example, the so-called disk changer, which accommodate one or more same kind of disks, is arranged so that the management information contained in the disk stored therein is managed by a device connected outside such as a host computer. The disk stored in the disk changer is managed under the title added to each disk by the host computer. The management of the disk is often realized by the application run in the host computer.
There has been conventionally known a non-changeable CD-ROM (compact disk for read only memory) drive having a capability of loading only one CD-ROM in a disk tray and a SCSI-1 interface so that the CD-ROM drive may be controlled from the host computer.
However, the SCSI-1 interface does not provide a capability of controlling the so-called changeable CD-ROM drive arranged to load two or more recording media so that a desirous medium may be selectively reproduced.
Further, the non-changeable CD-ROM drive has provided a capability of reproducing both of the CD-DA (Compact Disc for Digital Audio) and the CD-ROM (Compact Disk for Read-only Memory). In actual, however, for discriminating a disk type, the host computer cannot recognize it until the disk drive reproduces a TOC (Table of Content) area that corresponds to a management area and transfer the reproduced identifier to the host computer through the SCSI-I interface.
Today, many kinds of recording media are prevailing in the society. Concretely, many disklike recording media having various kinds of writing functions have been proposed such as a read-only disk, a write-only disk and a rewritable disk.
In this circumstance, there has been increasingly enhanced a request for storing different kinds of disks in one disk changer. As a result, it is necessary to consider that a request is rising for discriminating each disk type of recording media loaded in the disk changer.
For example, the disk type may be discriminated on the identifier recorded in the TOC (Table of Content) that is served as a management area on the disk. A higher laser power than a given level may erroneously erase the recorded content. In place, since the management of the disk is often realized by the application run on the host computer as mentioned above, it is considered that each type of the disks loaded in the changer may be registered in the storage device such as a harddisk drive located in the host computer. In this case, when reading or writing the data from or on the disk or retrieving it, the registered data may be used for the purpose.
However, in a case that the disk to be stored in the disk changer is managed by the data registered in the host computer, this kind of management is effective only when the combination of the disk changers connected to the host computer is fixed. If another combination is connected to the host computer, it is necessary to replace the data registered in the host computer.